Appraisal Square Footage HIGHER than MLS Listing

[Jack Browning]

Hello!

Looking for some insight on this unique situation - I tried to search for answers online and completely struck out. There are tons of responses for what to do when the appraisal comes back with a LOWER square footage figure vs. the advertised MLS listing, but what about the opposite case?

My investing partner recently obtained an appraisal for a property, and compared to the original listing, the square footage is significantly HIGHER. The house is 3 stories with a recently half-finished basement. My assumption is the city assessment stating it was '2.5 stories' simply took the building footprint and multiplied by 2.5. This didn't account for an accurate reading of the "half story" on the third floor, or a recently renovated half basement. The difference between the appraisal and the listing is 1,200 additional sq ft.

The house is priced at a multiple that makes sense for the original square footage listed given the area, but applying that same multiple (or even a decent bit lower) to the appraiser's higher estimated size would get a significantly higher value.

Could a buyer be sitting on a windfall that the seller missed? Or would this for some reason not affect the value meaningfully?

Any insight is welcome.